Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method for noise suppression in digital X-ray images, comprising: acquiring an original image; estimation of a signal-dependent noise variance dependent on signal intensity; combined bilateral non-local filtering; suppressing residual low-frequency noise; and over-smoothing correction, wherein the estimation of a signal-dependent noise variance dependent on signal intensity comprises: morphological elimination of the values of noise image pixels corresponding to edges in the original image; using robust piecewise linear approximation of interval estimations of noise variance to obtain a tabulated function of dependence of noise on signal strength; and calculating a noise map as a pixel-by-pixel estimation of noise variance in the original image; wherein the combined bilateral non-local filtering comprises averaging by combining non-local means filter and bilateral filter weights; wherein suppressing residual low-frequency noise comprises using a pyramid method with filtering of low-frequency by a bilateral filter; further comprising obtaining a result image; and wherein the over-smoothing correction comprises combining the final image and the original image based on structural and pixel similarity between the filtered image and the original image.
A method for reducing noise in digital X-ray images involves several steps. First, it acquires the original X-ray image. Then, it estimates noise variance based on signal intensity, removing noise pixel values corresponding to edges via morphological operations, approximating interval estimations of noise variance using a robust piecewise linear method to create a tabulated function, and calculates a noise map. Next, it applies combined bilateral non-local filtering by averaging with a combination of non-local means filter and bilateral filter weights. After that, it suppresses residual low-frequency noise using a pyramid method with bilateral filtering of low-frequency components. Finally, it corrects over-smoothing by combining the filtered image and the original image, based on both structural and pixel similarity, to produce a result image with reduced noise and preserved details.
2. The method of claim 1 , further comprising calculating the averaging weights for combined bilateral non-local filtering using the original image smoothed by a linear low frequency filter.
The noise reduction method for digital X-ray images, as described previously, includes calculating averaging weights for the combined bilateral non-local filtering step. This weight calculation uses the original image, but first, it's smoothed by a linear low-frequency filter. The method acquires an original image; estimates signal-dependent noise variance; performs combined bilateral non-local filtering; suppresses residual low-frequency noise; and corrects over-smoothing to obtain a result image. The combined bilateral non-local filtering weights are thus determined from this pre-smoothed original image.
3. The method of claim 1 , wherein the combined bilateral non-local filtering comprises using a combined weight function as fixed weight fractions for the non-local means filter and the bilateral filter, wherein these filters are combined at a final stage.
The noise reduction method for digital X-ray images, as described previously, uses a combined weight function for the combined bilateral non-local filtering step. This weight function applies fixed weight fractions to both the non-local means filter and the bilateral filter, combining the filters at the final stage. The method acquires an original image; estimates signal-dependent noise variance; performs combined bilateral non-local filtering; suppresses residual low-frequency noise; and corrects over-smoothing to obtain a result image. In this version, these filters are combined at a final stage, using the specified weight function, for efficient noise reduction.
4. The method of claim 1 , wherein the combined bilateral non-local filtering comprises using a separable version of the bilateral filter for separation of the non-local means filter and the bilateral filter.
The noise reduction method for digital X-ray images, as described previously, uses a separable version of the bilateral filter for the separation of the non-local means filter and the bilateral filter within the combined bilateral non-local filtering step. The method acquires an original image; estimates signal-dependent noise variance; performs combined bilateral non-local filtering; suppresses residual low-frequency noise; and corrects over-smoothing to obtain a result image. By using a separable bilateral filter, the computational complexity of the filtering process is reduced, allowing for faster processing times without significantly compromising image quality.
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October 28, 2014
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